1. Technical Field
Embodiments described herein relate generally to a negative electrode active material for a non-aqueous electrolyte secondary battery cell, a non-aqueous electrolyte secondary battery cell, a battery pack and a method for manufacturing a negative electrode active material for a non-aqueous electrolyte secondary battery cell.
2. Description of the Related Art
Recently, with the rapid development of miniaturization technology of electronic devices, various portable electronic have been in wide-spread use. Also, as miniaturization is also required in batteries serving as power sources for the portable electronic devices, non-aqueous electrolyte secondary batteries having a high energy density draw attention.
In particular, attempts have been made to use a material having a high lithium absorption capacity and a high density, for example, an element which forms an alloy with lithium, such as silicon and tin, amorphous chalcogen compounds, and the like. Among them, silicon may absorb lithium atoms in a ratio up to 4.4 atoms per one silicon atom, and the negative electrode capacity per mass is about 10 times as large as that of graphitic carbon. However, since the volume of silicon greatly varies due to intercalation and deintercalation of lithium in a charge-discharge cycle, particles of the active materials are finely pulverized, which would affect cycle life of a battery.